0_xBadFace  // invalid: _ must separate successive digits
</pre>


<h3 id="Floating-point_literals">Floating-point literals</h3>

<p>
A floating-point literal is a decimal or hexadecimal representation of a
<a href="#Constants">floating-point constant</a>.
</p>

<p>
A decimal floating-point literal consists of an integer part (decimal digits),